Sufficient hydration is important for replacing bodily fluids during extended periods of aerobic activity, such as cycling. Currently, several methods are known for getting fluids to a person engaged in aerobic activity and in need of fluid replenishment. In an attempt to overcome the deficiencies of water bottles, personal hydration systems have been developed that include a reservoir for holding fluid, a flexible drink tube for conveying the fluid from the reservoir to the person engaged in aerobic activity, and a mouth-operated valve attached to the end of the tube. Reservoirs for hydration systems are generally made from sheets of flexible materials that have been sealed at their edges to provide a watertight container. Soft-side reservoirs or bladders are relatively inexpensive, can be comfortably worn within in a back pack or waist pack, and withstand impact well.
Hydration system bladders typically include a closeable fill port and a drain port that connects to the drink tube. Configurations for the hydration bladder fill ports include screw cap ports welded to one side of the bladder or into the bladder seam. Another approach is to fill through an open seam at the top of the bladder and employ a zipper type or roll-top closure that seals in the fluid.
The various types of fill ports are designed meet certain needs of bladder-based hydration systems. Screw top ports offer secure, robust closing method that is familiar to users. Welding ports to the bladder material is a low-cost manufacturing method that integrates into the processes employed in forming and sealing the bladder edges. Roll and zip top closures offer a wide opening for filling and adding ice to the bladder and facilitate cleaning and drying.
Despite the capabilities of current bladder fill port designs, there remain problems associated with their use. For example, screw-ports welded to the bladder's side can be oversized to offer easier filling, but their side-facing orientation can make them difficult to fill under a faucet. Side-mounted ports can require that the bladder be removed from its hydration pack for filling. Cleaning and drying bladders made with side-mounted fill ports can be troublesome due to the size of the port opening and the tendency of the bladder sides to collapse together. Seam-welded ports can be placed at the top of the bladder, but can be more difficult to weld reliably and can become bulky when made with oversized openings. Roll and zip top closures may not seal as reliably as screw-top closures and may require extra effort to keep them opened during filling.